1. Technical Field
The present invention relates to an image forming device, such as a copier or a printer or the like, which employs an electrophotographic method. In particular, the present invention relates to a cleaning device which cleans a charging roller which charges the surface of an image carrier which is driven to rotate, and to an image forming device which is equipped with the cleaning device.
2. Related Art
In a contact-charging method which carries out charging of an image carrier by causing a conductive charging roller to directly contact or to be very close to an image carrier, the generating of ozone and nitrogen oxides is greatly decreased, and the power source efficiency thereof also is good. Therefore, the contact-charging type method has become the mainstream method recently for charging devices of image forming devices, such as copiers or printers or the like, which employ an electrophotographic method.
In such a contact-charging method charging device, because the charging roller is always contacting or is always extremely close to the image carrier, there is the problem that it is easy for contamination due to foreign matter adhering to the surface of the charging roller to arise. Namely, at the downstream side of the transfer process, the surface of the image carrier, at which the image forming operation is repeatedly carried out, goes through a cleaning process which removes foreign matter such as residual toner and the like after the transfer, and thereafter, enters into the region of the charging process. However, even after going through the cleaning process, minute particles which are smaller than the toner, such as portions of the toner or external additives of the toner or the like, remain on the image carrier without being cleaned-off, and adhere to the surface of the charging roller. The foreign matter adhering to the surface of the charging roller causes non-uniformity in the surface resistance value of the charging roller, and is a cause of abnormal discharging or unstable discharging, and causes the uniformity of charging to deteriorate.